Shortening 7T MP2RAGE acquisition with compressed sensing: Evaluating quantitative accuracy and structural...

Area of Science:

• Magnetic Resonance Imaging
• Quantitative Imaging
• Biomedical Engineering

Background:

• Ultra-high field (UHF) MRI enables advanced imaging but faces challenges with long acquisition times.
• Magnetization-prepared 2 rapid acquisition gradient echo (MP2RAGE) is a key sequence for quantitative T1 mapping.
• Compressed sensing (CS) and parallel imaging (PI) are acceleration techniques to reduce scan duration.

Purpose of the Study:

• To systematically evaluate compressed sensing (CS) for MP2RAGE at ultra-high fields.
• To assess the impact of CS on acquisition time, image quality, T1 mapping accuracy, and segmentation consistency.
• To compare CS-MP2RAGE with PI-MP2RAGE (GRAPPA).

Main Methods:

• MP2RAGE sequences were acquired using CS and GRAPPA with varied undersampling factors and samples per repetition time (TR).
• Acquisition time, T1 mapping accuracy, and segmentation consistency across regions of interest (ROIs) were quantitatively assessed.
• Image quality and reconstruction stability were evaluated.

Main Results:

• CS-MP2RAGE reduced acquisition time by 61% (< 3 min) compared to PI-MP2RAGE, maintaining comparable image quality and T1 mapping fidelity.
• Higher undersampling factors reduced scan time but introduced segmentation mismatches (up to 20%) and increased T1 values.
• Optimizing samples per TR enhanced image quality, enabling higher undersampling without significant fidelity loss, though very low densities destabilized reconstruction.

Conclusions:

• CS-MP2RAGE is a viable alternative to GRAPPA for UHF applications, significantly reducing scan time while preserving image quality and quantitative accuracy.
• The interplay between undersampling factors and samples per TR is critical for optimizing scan efficiency in CS-MP2RAGE.
• Further exploration of CS-MP2RAGE in clinical and research settings is warranted.